No, that's not the same at all...
MS coming in to help optimise Destiny, thus making Bungie work longer on PS4 would give us a forever cycle and the game would never get released. The PS4 version matched their vision, and they tried to get the Xbone there but couldn't. Doing more to the PS4 version (without, I dunno, help from Sony?) would cost extra money for absolutely no reason.
"Absolutely no reason"? The reason would have been to please a very small minority! That's definitely worth it!